The vacuum, countergravity, shell mold casting process is particularly useful in the making of thin-walled castings and involves: sealing a bottom-gated mold, having a gas-permeable upper portion, to the mouth of a vacuum chamber such that the chamber confronts the upper portion; immersing the underside of the mold in an underlying melt; and evacuating the chamber to draw melt up into the mold through one or more of the gates in the underside thereof. Such a process is shown in U.S. Pat. No. 4,340,108 wherein the mold comprises a resin-bonded-sand shell having an upper cope portion and a lower drag portion sealingly bonded together and attached to the vacuum chamber by means of spring clips which engage a peripheral abutment on the outside of the vacuum chamber. U.S. Pat. No. 4,340,108 seals the mold to the vacuum chamber atop the cope such that the parting line between the mold halves lies outside the vacuum chamber. Copending U.S. Pat. application Ser. No. 654,404, filed September 26, 1984 in the name of Roger Almond and assigned to the assignee of the present invention, seals the mold to the vacuum chamber atop the drag such that the parting line between the cope and drag falls within the vacuum chamber. U.S. Ser. No. 654,404 uses spring biased bolts engaging the underside of the drag and extending along the outside of the vacuum chamber to secure the mold to the vacuum chamber. The heads of the bolts are immersed in the melt and accordingly have a very short useful life. Finally, Chandley G. D., Automatic Counter Gravity Casting of Shell Molds, Modern Casting, October 1983, pages 29-31, describes a technique for mounting round molds to a round vacuum chamber wherein the inside surface of the vacuum chamber includes self-tapping threads which screw into the periphery of the round mold. The latter technique has been restricted to relatively small molds and cannot be used with molds which are rectangular or have other than a round exterior.
It is an object of the present invention to provide apparatus for the vacuum, countergravity casting of shell molds including improved means for automatically mounting the shell mold to the mouth of the vacuum box without deterioration of the mounting means and regardless of the shape or size of the mold and the vacuum chamber. This and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.